Gas-phase reactors for processing substrates, such as semiconductor wafers, often include a susceptor within a reaction chamber. During processing, one or more substrates are placed within the reaction chamber and onto the susceptor using a robotic arm. After processing, the substrate(s) are removed from the surface of the susceptor and through an opening in the reaction chamber using the robotic arm.
Often, it is desirable to maintain a relatively small reaction space or region within the reaction chamber. The relatively small reaction space allows for more-efficient substrate processing. For example, a smaller amount of reactants can be used when processing substrates in a relatively small reaction space—compared to a larger reaction space and/or an amount of time to process substrates using the relatively small reaction space can be less than the amount of time to process substrates in the larger reaction space. To allow for a relatively small reaction space within a reaction chamber, while allowing placement of substrates onto the susceptor and removal of the substrates from the susceptor, a reaction chamber often includes a separate wafer transfer region that includes the opening within the reaction chamber to allow placement on and removal of the substrates from the susceptor.
During the substrate transfer process, lift pins, which extend through a vertical width of the susceptor and beyond, are sometimes used to facilitate placement and removal of the substrate on and from the surface of the susceptor. In such cases, a substrate can be placed onto the susceptor by placing (lowering) the susceptor to be within the substrate transfer region of the reaction chamber, causing the lift pins to rise above the surface of the susceptor, placing the substrate onto the lift pins, and lowering the lift pins, such that the substrate rests on the susceptor. The susceptor and the substrate can then be moved (raised) to a processing position, such that the substrate is within the reaction region of the reaction chamber.
Although such techniques work relatively well to place substrates within and remove substrates from a reaction space within the reactor, mechanisms to move the susceptor and the lift pins are relatively complex. In addition, reactors employing such techniques can exhibit undesired gas flow between the reaction region and the substrate transfer region—especially during substrate processing. The undesired gas flow can lead to deposition and/or corrosion of the reactor within the substrate transfer region. Furthermore, the volumes of such reactors are relatively large to accommodate both the processing/reaction region and the substrate transfer region of the reaction chamber. In addition, the multi-step process of moving the susceptor to a transfer region and moving the lift pins is a relatively time consuming. Accordingly, improved mechanisms and techniques for transferring and processing substrates are desired.